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GI Physiology > Exam 3 (Oral Digestion, Deglutition, Gastric Motility) > Flashcards

Exam 3 (Oral Digestion, Deglutition, Gastric Motility) Flashcards

1
Q

Term for “precipitate of food & saliva”

A

plaque

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2
Q

Tooth decay causes formation of _____.

A

plaque

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3
Q

_____ and ____ are produced by bacteria which demineralize enamel and attack protein matrix (tooth decay).

A

lactate
protease

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4
Q

What is the term for “demineralized enamel and attack of protein matrix”

A

cavities aka caries

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5
Q

What substance is in toothpaste that replaces OH groups on hydroxyapatite and kills bacteria?

A

fluoride

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6
Q

Lactic acid demineralizes enamel by dissolving _____ in tissue (teeth + bones).

A

CaPO4

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7
Q

What is known as the conditioned or learned reflex involved in oral digestion?

A

chew reflex

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8
Q

(T/F) Mastication is entirely voluntary.

A

False - mainly voluntary but has involuntary component

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9
Q

Stimulus of Chew Reflex

A

presence of food in mouth

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10
Q

Chew reflex (stimulates/inhibits) motor neurons of the jaw musculature.

A

inhibits

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11
Q

Chew reflex causes reflex (relaxation/contraction) of the jaw.

A

contraction

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12
Q

Clinical relevance to chew reflex

A

chewing/stretching jaw while intubating animal

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13
Q

Term for “combined secretions of paired salivary glands (parotid, sublingual, submandibular)”

A

saliva

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14
Q

2 secretory cell types of salivary glands

A
  1. parotid (serous - watery saliva)
  2. sublingual/submandibular (mucoserous - thicker)
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15
Q

(T/F) There is small tonic activity of saliva flow in most species between meals but the ruminant has high flow to buffer the rumen.

A

True

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16
Q

With meal intake, there is a large (increase/decrease) in salivation.

A

increase

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17
Q

Source of saliva

A

extracellular fluid volume

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18
Q

(Carnivores/herbivores/omnivores) has much greater saliva production/output due to their dietary niche.

A

herbivores

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19
Q

Match amount of saliva production to species:

Horse
Cattle
Dog
Man

A

10 gal/day
40 gal/day
0.5 qt/day
1.5 qt/day

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20
Q

Match osmolarity of ECF:
(300 mOsm/L | <300 | > 300)
isotonic
hypotonic
hypertonic

A

300
<300
>300

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21
Q

Saliva is used in clinical pathology testing to measure _____ in cattle.

A

heavy metals / chronic lead poisoning

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22
Q

What clinical signs are seen with lead poisoning in cattle? Why?

A

neurological signs, blue line near gums
drinks lead water –> lead combines with teeth plaque

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23
Q

In non-ruminants, saliva is (hypotonic/hypertonic/isotonic) at low salivary flow rates.

A

hypotonic

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24
Q

What are the main ions in saliva of non-ruminants? (4)

A

Na+
Cl-
HCO3-
K+

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25
Q

Saliva in non-ruminants (basic/acidic) at low flow rates.

A

acidic

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26
Q

The primary secretion of saliva is in the _____ of the salivary gland while the secretion is modified in the _____.

A

acini
duct

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27
Q

What transporters are used to modify saliva secretions in the salivary duct?

A

Na/H, Na/K, Na/Cl exchangers
K+ secretion

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28
Q

Saliva secretions are modified in the salivary duct only at (low/high) saliva rates.

A

low

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29
Q

If saliva is high flow rate and bypasses modifying transporters, the saliva at the end will be similar to __________ concentration.

A

extracellular fluid volume

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30
Q

What 3 ions are part of the primary salivary secretion at the acinus?

A

Na, Cl, HCO3

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31
Q

In ruminants, salivary flow is (hypotonic/hypertonic/isotonic) at all flow rates.

A

isotonic

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32
Q

In ruminants, salivary flow rate is (high/low) at resting flow rate and (higher/lower) when eating/ruminanting.

A

high
high

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33
Q

In ruminants, ____ is an important buffer in saliva at low flow rates and reciprocates with ____ at higher flow rates.

A

PO4-
HCO3-

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34
Q

Ruminant saliva gets closer to plasma concentration at (low/high) flow rates.

A

high

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35
Q

Ruminant saliva is (acidic/alkaline) with a pH of ____. For what purpose?

A

alkaline
8
buffers rumen pH (VFA)

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36
Q

Ruminants are constantly swallowing to neutralize _____.

A

VFA

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37
Q

pH of healthy rumen

A

6.5

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38
Q

What are the 4 organic components of saliva?

A

mucin
ptyalin
urea
bacteriocidal compounds

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39
Q

Ptyalin is a salivary ______ and only present in (carnivores/herbivores/omnivores).

A

amylase
omnivores

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40
Q

Ptyalin hydrolyzes ____ to _____ which is why bread gets sweeter as you chew.

A

starches
maltose

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41
Q

_____ is important in recycling of the ruminant and passively moves blood into the salivary duct.

A

urea

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42
Q

Urea is lipid (soluble/insoluble) and from ____ of the liver.

A

soluble
ammonia

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43
Q

What are 2 bacteriocidal compounds of saliva?

A

lysozymes (kill bacteria)
secretory antibody (IgA)

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44
Q

Why can licking wounds be beneficial?

A

secretory antibody (IgA) in saliva can kill some bacteria

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45
Q

What is an important source of nitrogen for bacteria of the microbiota needed for growth?

A

urea

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46
Q

Control of salivation is mainly ____.

A

neural (ANS - PSNS + SNS)

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47
Q

What kind of reflexes are in association with preparation for eating?

A

conditioned reflexes

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48
Q

Example of conditioned reflex

A

pavlov effect

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49
Q

What 3 types of input are a part of conditioned reflexes for control of salivation?

A

visual
auditory
olfactory

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50
Q

Unconditioned reflexes for salivation have a(n) _____ and _____ portion.

A

oral
abdominal

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51
Q

Stimulus for unconditioned reflexes (oral portion)

A

chemical + mechanical presence of food in mouth

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52
Q

What 2 receptors sense presence of food in mouth for unconditioned oral reflex for salivation?

A

tactile receptors
taste receptors

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53
Q

Unconditioned reflexes (abdominal portion) for salivation in most animals is associated with _____ stimuli.

A

noxious
(salivate when nauseous)

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54
Q

Why do you salivate when nauseous?

A

salivary center closely linked with vomiting center

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55
Q

3 receptor types in the unconditioned reflexes of salivation (abdominal portion)

A

esophageal
gastric
intestestinal

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56
Q

In the ruminants, ______ in the ____ (part of stomach) stimulates salivation - abdominal portion of unconditioned reflex.

A

fibrous material
cardia

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57
Q

(T/F) All glands receive PSNS & SNS nerves from the CNS.

A

True

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58
Q

What are the PSNS + SNS nerves for salivation from the CNS called?

A

salivary nuclei

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59
Q

Daily efferent output is a mixture of PSNS + SNS control but (PSNS/SNS) dominates fluid content while (PSNS/SNS) dominates releasing salivary enzymes/mucus.

A

PSNS
SNS

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60
Q

PSNS controls _____ of salivation.
SNS controls ___ and ___ of salivation.

A

fluidity
mucous + enzymes

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61
Q

Isolated effect of PSNS on saliva (2)

A
  1. copious watery saliva
  2. indirect vasodilation
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62
Q

Example of overdosing and having isolated effect of PSNS on saliva

A

overdose organophosphate insecticide
= down cholinesterase, up Ach = hypersalivation

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63
Q

In isolated effect of PSNS on salivation, indirect vasodilation occurs via _____ which leads to increased secretion and saliva flow.

A

bradykinin

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64
Q

Isolated effect of SNS on salivation (2)

A
  1. thick, mucus saliva (direct)
  2. vasoconstriction
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65
Q

Example cause of isolated SNS effect on salivation

A

aggressive/excitable dog –> thick mucousy saliva

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66
Q

In isolated effect of SNS on salivation, vasoconstriction occurs due to a _____ effect which decreases primary secretion.

A

alpha adrenergic

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67
Q

What hormone has a systemic influence on salivation?

A

aldosterone

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68
Q

Aldosterone increases is there is an increase in what 3 things?

A
  1. dehydration
  2. hemorrhage
  3. salt-deprivation
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69
Q

Four outcomes of aldosterone on distal salivary duct

A
  1. up Na+ reabsorption
  2. up K+ secretion
  3. down bloodflow to salivary gland
  4. down saliva output
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70
Q

Which species does aldosterone especially have an effect on in terms of salivation?

A

ruminants

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71
Q

What things increase to increase Na+ reabsorption via aldosterone?

A

Na+ & K+ channels
Na+ pumps

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72
Q

4 functions of saliva in all species

A
  1. soften/lubricates food
  2. oral hygiene
  3. dissolve chemicals (for taste)
  4. thirst sensation
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73
Q

In pigs + humans, _____ in saliva allows for starch digestion.

A

ptyalin

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74
Q

What special function does saliva offer to dog/cat that is not in other domestic mammals?

A

evaporate cooling (10x salivation rate)

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75
Q

What 2 special functions does saliva have for ruminants?

A
  1. buffers VFA (in rumen)
  2. recycles urea (nitrogen source)
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76
Q

Taste buds are ____ bodies composed of what?

A

ovoid
hair cells + unmyelinated sensory nerve endings

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77
Q

What 4 structures are taste buds distributed on?

A

epiglottis
palate
pharynx
tongue

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78
Q

5 tastes of humans

A
  1. salty
  2. sour
  3. sweet
  4. bitter
  5. umami (savory)
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79
Q

What tastes do we have high threshold for? Which is lowest?

A

salty/sweet
bitter

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80
Q

Why do we have a low threshold for bitter taste?

A

sense possible plant alkaloids (toxin)

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81
Q

Salt taste modality

A

Na+ (via Na+ channel + ENAC)

82
Q

Sour taste modality

A

protons (organic acids)

83
Q

Sweet taste modality

A

hexose
via Tas1r2/3 GPCRs
release ATP to afferent N

84
Q

Which species have a loss of function mutation to sweet tastes?

A

carnivores (big cats, dolphins)

85
Q

Example of sour organic acid

A

acetic acid

86
Q

Bitter taste modality

A

organic cations
–> release ATP to afferent N

87
Q

Example of organic cation for bitter taste

88
Q

Savory/umami taste modality

A

glutamate receptor
–> release ATP to afferent N

89
Q

What 3 tastes release ATP to afferent nerves?

A

sweet
bitter
savory/umami

90
Q

Term for “ability to distinguish tastes/flavors”

A

taste acuity

91
Q

(T/F) Taste acuity correlates with the number of taste receptors (taste buds).

A

False - does not correlate

92
Q

3 influences on taste acuity

A
  1. stim. of taste receptors
  2. smell
  3. food temperature
93
Q

Term for “drive to eat or drink”

A

nutritional widsom

94
Q

4 drives for nutritional wisdom

A
  1. regulate energy intake
  2. water taste
  3. salt appetite
  4. other nutrients
95
Q

What is the #1 drive to eat or drink?

A

regulation of energy intake

96
Q

Term for abnormal appetite

97
Q

Term for swallowing

A

deglutition

98
Q

Term for “common opening to trachea + esophagus”

A

oropharynx

99
Q

Considering the oropharynx, you must be able to swallow without _____.

A

aspiration

100
Q

Deglutition is a highly complex reflex requiring _____.

A

6 cranial nerves

101
Q

3 main phases of swallowing (which are voluntary/involuntary?)

A
  1. oral phase (voluntary)
  2. pharyngeal phase (involuntary)
  3. esophageal phase (involuntary)
102
Q

Steps of oral phase of deglutition

A
  1. food bolus forms
  2. positioned on back of tongue
  3. rostral tongue pressed to hard palate, jaw closes –> forces bolus into oropharynx
103
Q

Steps of oral phase of deglutition

A
  1. food bolus forms
  2. positioned on back of tongue
  3. rostral tongue pressed to hard palate, jaw closes –> forces bolus into oropharynx
104
Q

Function of pharyngeal phase of deglutition

A

move bolus from oropharynx –> esophagus

105
Q

Stimulus of pharyngeal phase of deglutition

A

bolus pushed by tongue –> oropharynx

106
Q

Afferent impulses from pressure receptors in oropharynx go to ______ in the medulla/pons that coordinates response (pharyngeal phase of deglutition).

A

swallowing center

107
Q

Efferent action of pharyngeal phase of deglutition

A

soft palate- constrictor Mm close off nasopharynx

108
Q

During deglutition, airway opening is (open/closed) and ____ is inhibited for a second to prevent entry of food bolus.

A

closed
respiration

109
Q

During deglutition, there is contraction of _____ and ____ Mm.

A

pharyngeal
laryngeal

110
Q

3 actions that occur from contraction of pharyngeal + laryngeal Mm during deglutition

A
  1. larynx raises
  2. glottis closes
  3. epiglottis covers glottis
111
Q

Contraction of _____ muscles propels bolus through ______ as it relaxes briefly.

A

pharyngeal Mm
upper esophageal sphincter (UES)

112
Q

After bolus moves through UES, breathing resumes and the bolus entry into upper esophagus initiates ________.

A

involuntary esophageal phase

113
Q

What 3 steps occur within the esophageal phase of deglutition?

A
  1. primary esophageal peristalsis
  2. secondary esophageal peristalsis
  3. tertiary esophageal peristalsis
114
Q

During primary esophageal peristalsis, there is (relaxation/contraction) behind the bolus and (relaxation/contraction) in front of the bolus.

A

contraction
relaxation

115
Q

Relaxation of _____ occurs after the bolus enters the body of the esophagus and remains open until _______ passes.

A

lower esophageal sphincter (LES)
ring of contraction

116
Q

LES closes completely to prevent ____.

A

gastric reflux

117
Q

(T/F) Secondary esophageal peristalsis always occurs after primary.

A

False - only if needed to clear bolus

118
Q

What 2 things induce secondary esophageal peristalsis?

A
  1. uncleared bolus
  2. gastric content / reflux
119
Q

In secondary esophageal peristalsis, afferent impulse originates from ______.

A

esophageal body at bolus (NOT UES!)

120
Q

_____ esophageal peristalsis is in the _____ muscle portion of esophagus and acts (systemically/locally) via _____ nervous system.

A

tertiary
smooth
locally
esophageal enteric

121
Q

Where should an orogastric feeding tube be placed? Why?

A

proximal to LES
so LES can open/close normally

122
Q

Esophageal muscle in birds

A

all smooth muscle (gravity helps)

123
Q

Esophageal muscle in humans/horses

A

2/3 skeletal, lower 1/3 smooth

124
Q

Esophageal muscle in dog/cat

A

mostly skeletal (some smooth near LES)

125
Q

Esophageal muscle in ruminants

A

short segments of smooth M (esophagus groove)

126
Q

Esophageal muscle in rodents

A

all striated (highly controlled)

127
Q

Peristaltic movement is highly coordinated in the esophagus due to central control from swallowing center which acts through ____.

128
Q

(Extrinsic/Enteric) innervation dominates control of esophageal peristalsis.

129
Q

Skeletal muscle esophagus neural control in order

A

swallow center –> GVE nerve (vagal motor N) –> skeletal M

130
Q

Skeletal muscle neural control is by (SNS/PSNS) and at the ____ neuromuscular junction.

A

PSNS
nicotinic

131
Q

For skeletal muscle esophagus, there is __ motor nerve fiber per __ skeletal M fiber which means (little/lots of) control.

132
Q

Name for striated muscle disease and disease example

A

Vagotomy
myasthenia gravis (autoimmune attach motor endplates for NMJs = difficulty swallowing)

133
Q

Disorder for esophageal amotility if vagus N is cut which causes “food packing”

A

megaesophagus

134
Q

Smooth muscle esophagus/LES neural control order

A

swallow center –> vagal PS N –> intrinsic plexi –> effector neurons –> smooth muscle

135
Q

Which type of muscle in the esophagus has serial contractions by coordination of the ENS?

A

smooth muscle / LES

136
Q

Neural control of the smooth muscle esophagus coordinate with _____ ______ which affects (circular/longitudinal) M while inhibitory nerves relax (circular/longitudinal) M.

A

muscarinic cholerinergic
longitudinal
circular

137
Q

If you cut both vagi, you will only have ____ esophageal waves.

138
Q

What is the main function of the lower esophageal sphincter (LES)?

A

prevent gastric reflux
relax during swallowing reflex

139
Q

Lower esophageal sphincter is (relaxed/contracted) at rest and (relaxed/contracted) during swallow.

A

contracted
relaxed

140
Q

During sustained contraction of LES at rest, (circular/longitudinal) smooth muscle via inhibitory nerves is (on/off). On the other hand, (circular/longitudinal) smooth muscle via cholinergic nerves is (on/off).

A

circular
off
longitudinal
on

141
Q

When LES relaxes during swallow, inhibitory effectors are (on/off) while cholinergic effectors are (on/off).

142
Q

In the LES, circular smooth muscle is known as ____ fibers while longitudinal is known as ____ fibers.

A

clasp
sling

143
Q

After a meal, _______ is increased to help enhance contraction of LES to prevent reflux.

A

plasma gastrin

144
Q

During interdigestive period, ____ are present at LES.

A

MMCs (migrating motor complexes)

145
Q

What 4 anatomical components are present to help LES to reduce reflux?

A
  1. flutter valve (intraabd esophagus)
  2. diaphragm pinching
  3. esophagus enters stomach at angle
  4. excessive gastric mucosa (horse)
146
Q

Why can’t horses vomit?

A
  1. more acute esophageal angle
  2. excessive cardia mucosa
  3. high LES tone (more smooth M)
147
Q

Term for “failure of LES to open”

148
Q

2 motor functions of the simple stomach (oral/proximal part)

A
  1. receive ingested food
  2. accommodation (storage)
149
Q

2 motor functions of simple stomach (distal part)

A
  1. mix/grind contents
  2. control propulsion
150
Q

Gastric digestion involves the formation of ______ (liquid of dissolved food + HCL + pepsin).

A

acid chyme

151
Q

During digestion, ingesta is formed into _______.

A

concentric spheres

152
Q

The (first/last) eaten food is up against gastric mucosa while the (first/last) eaten is in the middle.

153
Q

(T/F) In the proximal stomach, basic motility pattern is phasic, not tonic.

A

FALSE - tonic not phasic

154
Q

What does it mean that the proximal stomach is tonic not phasic?

A

no peristalsis
tonic contractions as stomach empties

155
Q

_______ smooth muscle layer dominates in tonic contractions of the proximal stomach and is (contracted/relaxed) during a meal.

A

circular
relaxed (for storage)

156
Q

As the stomach empties, there is a(n) (increase/decrease) in circular smooth muscle tone in the proximal stomach.

A

increase (pushes content –> distal part)

157
Q

What 2 processes allows the proximal stomach to receive and store food?

A
  1. receptive relaxation
  2. accommodation
158
Q

Receptive relaxation of proximal stomach order of events

A

swallowing center –> vagus –> activated inhibitory effector neurons = relaxation of circular smooth muscle

159
Q

During accommodation, tension in the stomach wall can increase significantly without an increase in ______.

A

intragastric pressure

160
Q

Accommodation in proximal stomach order of events

A

gastric tension receptor –> CNS –> vagus –> activated inhibitory effector neurons = increase radius + tension

161
Q

During accommodation in the proximal stomach, there is the same increase in ___ and ___, so there is the same _____ at the esophageal sphincter.

A

radius
tension
pressure

162
Q

As the proximal stomach empties, accommodation (increases/decreases), inhibitory nerve action (increases/decreases), and circular smooth muscle contraction (increases/decreases). Why?

A

decreases
decreases
increases
forces residual content –> distal part

163
Q

In the distal stomach, basic motility pattern is peristalsis driven by ______.

164
Q

3 main functions of the distal stomach

A
  1. propulsion
  2. emptying
  3. retropulsion
165
Q

What occurs during propulsion (of distal stomach)?

A

pylorus opens so content can go in

166
Q

What occurs during emptying (of distal stomach)

A

pylorus is open
chyme exits
mixing + grinding

167
Q

What occurs during retropulsion (of distal stomach)?

A

pylorus narrows
moves solid matter

168
Q

Pigs are fed “fines” for fattening but decrease diet bulk which (increases/decreases) acid chyme and causes _____.

A

increases
proximal stomach ulcers

169
Q

What is the “fed pattern” in distal stomach?

A

volume/presence of food –> stomach empties faster

170
Q

What two things sense contents of food in the stomach?

A

mechanoreceptors
chemoreceptors

171
Q

What 2 things mediate gastric motility/emptying in distal stomach?

A
  1. neural activity
  2. hormones (gastrin)
172
Q

When mechanoreceptors + chemoreceptors sense food in stomach, they respond by (increase/decrease) motility in what 2 areas?

A

increase
stomach + colon

173
Q

What 2 neural stimuli lead to release of gastrin?

A

cholinergic neurons
GRP (gastrin releasing peptide)

174
Q

What 2 luminal stimuli lead to release of gastrin?

A

amino acids
increased pH (pH > 4)

175
Q

Response to gastrin

A

increased gastric motility + emptying

176
Q

What 2 things mediate feedback (inhibitory) control of gastric motility/emptying in distal stomach?

A
  1. enterogastric long reflex (neural)
  2. CCK + incretins (hormonal)
177
Q

What 3 receptor types stimulate afferent pathway for feedback/inhibitory control of distal stomach motility?

A
  1. duodenal osmoreceptors
  2. duodenal pH receptors
  3. stretch receptors
178
Q

Duodenal hypertonicity leads to (more/less) gastric emptying in distal stomach while hypotonicity leads to (more/less).

179
Q

Why does duodenal hypertonicity cause less gastric emptying?

A

allow more time to dilute content in the duodenum

180
Q

When duodenal pH is >3.5-4 there is (more/less) gastric emptying in the distal stomach. When pH is <3.5-4 there is (more/less) emptying.

181
Q

Why is there less gastric emptying of the distal stomach when the duodenal pH is <3.5-4?

A

time to neutralize acid w/ bicarb secretion + pancreatic juice

182
Q

When duodenum is full, there is (more/less) gastric emptying. When empty, there is (more/less) gastric emptying.

183
Q

Why is there less gastric emptying when duodenum is full?

A

time for passage of content in duodenum

184
Q

Reduced gastric motility/emptying is mediated by what 2 things?

A
  1. activation of SNS efferents
  2. deactivation of PSNS efferents
185
Q

CCK released by what 2 stimuli?

A

lipids of 12-18 C atoms
amino acids

186
Q

CCK is a _____ at the gastrin receptor.

A

partial agonist

187
Q

If high gastrin concentration in blood, (increase/decrease) gastric motility by CCK. If low gastrin, (increase/decrease motility.

A

decrease
increase

188
Q

GLP 1&2 release is stimulated by ____ in intestinal lumen.

189
Q

GLP 1&2 lead to (increase/decreased) gastric motility mainly by GLP (1/2).

A

decreased
1

190
Q

Order the following with how quickly of gastric emptying: (fastest to slowest)

low fat diets
high fat diets
liquid

A

liquid
low fat
high fat

191
Q

Between meals (interdigestive period) _____ clears bulk from stomach to large intestine.

A

MMCs (migrating motor complexes)

192
Q

Phase I MMCs

A

slow waves | no contraction

193
Q

Phase II MMCs

A

intermittent spiking of slow waves (spike potentials)

194
Q

Phase III MMCs

A

spikes at each crest of slow waves = train of peristaltic contractions

195
Q

Which hormones provides neurocrine cholinergic action in Phase III of MMCs?

196
Q

______ remains open to clear stomach during interdigestive period w/ MMCs.

197
Q

Phases of MMCs repeat every _____ and are immediately stopped by what?

A

2 hours
eating

198
Q

Tetanic contractions after 24 - 72 hours after stomach empties are known as:

A

hunger pangs

199
Q

Hunger contractions occur ______ hours after stomach empties by increasing phase ____ of MMCs.

200
Q

After 24 - 72 hours, intense rhythm of peristaltic contractions fuse into _____ contractions.

A

tetanic contractions

GI Physiology (6 decks)

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